This invention relates to a control system for a vending machine.
In a vending machine of a conventional type, a "shortage of change" display is conducted in case the amount of stored change becomes less than a predetermined amount, which is normally determined as a maximum required amount of change such, for example, as 90 yen, for the purpose of preventing an impossibility of paying out change to a purchaser.
The prior art method of detecting "shortage of change" uses an arrangement of a coin detection switch such as an empty switch located at a predetermined position of a change coin storage tube such as normally in the vicinity of a position which corresponds to the maximum required amount of change, for detecting "shortage of change" on the basis of the output of this switch.
One of the important factors for improving the vending efficiency of the vending machine is prevention of "shortage of change" to a maximum degree so as to always maintain the vending machine in a state in which it is capable of vending articles stored therein.
This factor is particularly important for a vending machine which has recently been developed that can handle a large amount of money for a single purchasing or vending operation. More particularly, such a new type of vending machine functions to continuously vend a plurality of articles upon selection by a purchaser in a single vending operation starting by insertion of coins by the purchaser and ending by depression of a clear button (or switch). As a result, a total vending price becomes a large amount and, accordingly, a total amount of the inserted coins becomes a large one.
It is probable that the larger the amount of money required for purchasing the article in the machine becomes the larger becomes the amount of change to be paid out or money to be returned upon cancellation of purchase of the article. Accordingly, there may frequently occur a "shortage of change" state unless a sufficient consideration is given to the aforementioned point in designing the vending machine.
It has recently been proposed to provide an auxiliary coin storage device specifically for paying out coins, which device will hereinafter be called an "auxiliary tube", for the purpose of ensuring provision of a sufficient amount of change coins.
The conventional vending machine originally had only a single coin storage tube as a change or payout coin storage device, which will hereinafter be called a "main tube", to which coins inserted by a purchasers are automatically supplied. The proposed method intends to sufficiently obtain change coins by additionally providing an auxiliary tube specifically for paying out coins manually supplied by a supervisor of the vending machine. A difficulty is found in this vending machine as to a method of detecting "shortage of change" with respect to the main and auxiliary tubes, and there has not yet been proposed an effective means for such detection. One may consider, for example, a method of attaching respectively the aforesaid empty switches to the main and auxiliary tubes. As the number of the main and auxiliary tubes increases, the number of the empty switches also increases. This not only increases cost, but requires a large space for mounting a large number of switches, resulting in bulkiness of the coin acceptor of the machine. Furthermore, if the aforementioned empty switches are provided at respective coin storage tubes, a coin payout operation is prevented when the amount of stored coins falls below the position of each switch, and accordingly, all vending operaions of the machine requiring payout of change are prohibited in a state wherein coins falling short of the predetermined amount are retained in the respective tubes. Since the total amount of the coins retained in the main and auxiliary tubes sometimes becomes such that it will be sufficient to pay out the change, this method is extremely inefficient in that the vending operation is stopped notwithstanding that change can be paid out.
Another difficulty takes place in a case where an auxiliary tube specifically for paying out coins is employed. That concerns a change over control between the coin payout tubes, i.e. control of when the main tube is to be changed over to the auxiliary tube or vice versa for paying out coins.
There has heretofore been proposed a method of providing a switch for detecting a switched position of the tubes to the main tube side in addition to the empty switch. If the number of stored coins in the main tube falls below the position of this switch for detecting the switching position, the switch becomes OFF so as to switch the tube for paying out the coins from the main tube to the auxiliary tube.
However, this method has a disadvantage that it requires a space for mounting the switch for detecting the switched position, and also has an additional disadvantage that as the number of tubes increases, the number of the switches for detecting the switched position of the tubes increases.